Upton Sinclair, a Socialist and muckraking journalist, wrote The Jungle in 1906 as an expose of the horrific working conditions of immigrants in the Chicago meatpacking industry of the time. The main character, Jurgis Rudkus, is an immigrant from Lithuania who, newly married, tries to survive by working for very low wages in a Chicago slaughterhouse. The working conditions are notoriously and shockingly bad, and Rudkus's family falls into decline after one child in the extended family dies of food poisoning and Jurgis's child drowns in a puddle. Rudkus's wife dies in childbirth, as does her second-born child when Rudkus cannot afford a doctor.
The public response to the book was overwhelming, but not in the way Sinclair had expected. Rather than becoming incensed about the working conditions of the characters in the novel, the public was alarmed by the conditions in which their food was produced. As a response, President Teddy Roosevelt commissioned the Neill-Reynolds Report, exposing the unsanitary conditions of food production, and Congress passed the Meat Inspection Act of 1907 to legislate clean conditions for meat production. In addition, the Pure Food and Drug Act, legislating accurate labeling for food and drug products, was passed in 1906. These were among the first national consumer protection laws in the United States. Sinclair said of the public response to his book and people's concern for the conditions of food production over the concerns of working immigrants, "I aimed at the public's heart, and by accident I hit it in the stomach."
The greatest significance of Upton Sinclair's grim The Jungle is that its publication aroused much public sentiment, which then led to federal legislation such as the Pure Food and Drug Act and improvements in working conditions for meat packers and other factory workers.
As a muckraker Upton Sinclair wrote The Jungle as an exposé of the horrible conditions of the meat-packing industry. Sinclair himself stated his purpose as that of informing Americans of "the inferno of exploitation" as he characterized American factories in the early 1900's. Specifically, Sinclair's focus is on the exploitation of immigrants in Chicago as they worked long hours, wading in steaming hot blood in sweltering days in the summer, and freezing conditions in the winter. Eventually, after coming to America in search of a hopeful new life, these immigrants find these hopes reduced to numbing poverty, degradation, and despair.
As Sinclair was himself a Socialist, in The Jungle he promotes his ideology that would end "wage slavery" and provide safety for those in dangerous trades. Many of these ideas helped to give rise to labor unions.